Record Dry Spell in parts of the Northeast and Mid-Atlantic

Drought conditions have intensified across the northeastern quarter of the country, and forecasts indicate
that significant relief is unlikely during the next 10 days.

Much of the Northeast and mid-Atlantic have received little or no rain since early August, exacerbating
long-term dryness that has persisted since mid-March, and in some areas since October, 1994. Severe short-term
dryness began after the remnants of Hurricane Erin traversed the mid-Atlantic on August 6. The ensuing 25 days
(through the 31st) brought only spotty light showers to most of the Northeast and mid-Atlantic, with no measurable
rain reported in several areas from north-central Virginia northeastward into the Boston, MA metropolitan area
(Figure 1). New York City reported no measurable rainfall for 24 consecutive days before dissipating
thundershowers dropped light rain on some areas late August 31. This broke the previous August record of 19
straight days set in 1938. New York City's Central Park measured a meager 0.18" of rain this August, erasing the
prior August record low of 0.24" in 1964. Similarly, LaGuardia (0.12") and JFK (0.22") Airports also set new
August records. Farther south, National Airport in Washington, DC recorded an August record of 25 consecutive
days without measurable rain, and the all-time record of 32 days set in 1963 was within reach. Unfortunately, none
of the copious rains (up to 20" near Greenville, SC) from the remnants of Tropical Storm Jerry did not reach any
farther north than central Virginia.

The cause of these unusual conditions over the last month can be attributed to a displacement of jet-stream
features from their climatologically-typical positions. Normally, a moderately strong upper-level ridge dominates
the central United States during August, with troughs positioned along both the Atlantic and Pacific Coasts. This
year, however, the trough along the Pacific Coast was abnormally strong and to the east of its normal position. This
forced the ridge well northeastward, becoming established along a Great Lakes/Hudson Bay axis, particularly
during the middle of the month. As a result, significant mid-latitude weather disturbances were shunted northward
from the West Coast toward central Canada, while tropical moisture was forced to the south, affecting the Gulf
Coast Region and Southeast. Late in the month, a strong upper-level trough formed over the northern Atlantic
Ocean south of Greenland. This established a northwesterly upper-level flow over the Northeast that allowed cool,
dry air to displace the hot conditions observed earlier in the month. The late-August weather pattern, unfortunately,
also suppressed rainfall in the region, so drought conditions continued.

The severe short-term rainfall shortages enhanced a pattern of persistently subnormal precipitation dating
back 6 to 11 months in much of the Northeast and mid-Atlantic. Most areas recorded less than 75% of normal
precipitation since March 12, with localized sections of New York, lower New England, and the eastern mid-
Atlantic observing under half of normal (Figure 2). Typically, 16 to 23 inches of rain falls on the Northeast and
eastern mid-Atlantic during March 12 - August 29, but only 10 to 15 inches were measured at most locations for
the 171-day period this year. Rainfall was particularly short in eastern and southeastern New York, northeastern
Pennsylvania, and southern Vermont, where only 5 to 11 inches were reported. Consequently, streamflows across
the Northeast were already below normal by the end of July (Figure 3) while localized intense rainfall led to
copious flows across the central and western mid-Atlantic during this period. Going back to October 1994, deficits
exceeded 8 inches at many locations, with shortages of 15 to 20 inches reported along the Atlantic Seaboard and
in upstate New York (Figure 4). In addition, above normal temperatures during much of the year, particularly
during July, contributed to enhanced surface evaporation in the Northeast.

All of these factors contributed to the current long-term moisture budget conditions across the region. The
long-term Palmer Drought Index (PDI) was less than -4 ("extreme drought") over parts of central and southern New
York, southern Connecticut, northeastern Pennsylvania, and the eastern mid-Atlantic on August 26 (Figure 5). Most
other sections of the Northeast were in "moderate" to "severe" drought (PDI between -2 and -4) while much of
central and western Virginia and West Virginia registered only slightly below normal in the long-term, primarily
because of the locally intense June and July rains.

Drought warnings were recently issued for several northern New Jersey counties, while drought watches
were extended to the lower Hudson River Valley, the Catskills, the Hudson Mohawk region, and the New York
City metropolitan area. The New York City reservoir system held about 67 percent of capacity
(Figure 6),
compared to the normal 81 percent of capacity in late August, when recharge is typically very low. Some small
municipal water systems with shallow wells have begun to issue water use restrictions. If conditions continue to
deteriorate, voluntary conservation measures will become more common, and in some areas, more specific
mandatory conservation measures will be necessary.

Most rivers and streams across the northeastern quarter of the nation are at about one-half of their normal
flow for this time of year. The flow on the Susquehanna River at Harrisburg is 29 percent of normal for late August,
and the Delaware River at Trenton is at 73 percent of normal flow. The Hudson River at Ft. Edward was running
at 29 percent of normal, and the Connecticut River at North Stratford was near 28 percent of normal.

The lack of rain on Long Island led to tinder dry conditions which aided the development of large wildfires,
reportedly the worst in 60 years according to local officials. These fires consumed about 6,000 acres of land. In
addition, fire danger advisories have been issued by the Pennsylvania Department of Conservation and Natural
Resources and the New York State Department of Environmental Conservation. According to the National
Interagency Coordination Center in Boise, ID, the current fire severity potential across most of New England and
the mid-Atlantic is in the high to very high risk category, with pockets of extreme risk.

Agricultural interests have thus far experienced the most significant and widespread impacts resulting from
the dry conditions. According to the Department of Agriculture, topsoil moisture across the Northeast and mid-
Atlantic were low to very low as of August 28, with some crops stressed due to the hot, dry weather. Late-planted
vegetable crops in New England are showing the greatest stress. Yield and quality prospects for corn and soybeans
are declining, with most crops reported in poor to very poor condition.

Generalized, regional short-term forecasts through Sep. 9 suggest little significant relief from the drought
conditions (Figure 7). The 5-day outlook (for Sep. 1-5) indicates slightly above normal temperatures and light to
moderate rainfall, and the 6-10 day outlook (for Sep. 5-9) calls for above to much above normal temperatures and
below to near normal precipitation. [Please note that these generalized outlooks describe average conditions over
large areas and time frames. For outlooks at specific locations, refer to the forecasts issued by the local NWS
Forecast Office]. There is no clear signal for relief of drought conditions in the longer-term outlooks for September
and the meteorological Autumn (September-November).